The present invention relates to a molding and apparatus and process for manufacturing the same.
Some of moldings for special purposes comprise three or more portions formed of different types of material. For example, as shown in FIG. 16, molding E comprises a first portion E1 formed of hard rubber, a second portion E2 formed of sponge rubber, and a third portion E3 formed of semihard rubber having a flexibility smaller than that of sponge rubber and greater than that of hard rubber. These portions E1, E2 and E3 are generally simultaneously and integrally formed as a unit.
A problem usually associated with such a molding E is that three types of rubber has to be prepared to form the molding E.
Another problem usually associated with the molding is that apparatus for manufacturing the molding has to include three special purpose machines to extrude hard rubber, sponge rubber and semihard rubber in order to form the molding E, thereby causing increased cost for the apparatus.